Plow guide for a chain-pulled plow

ABSTRACT

The subject matter of the present invention relates to a plow guide for a chain-pulled plow for use in underground mining operations, with plow guide troughs  20  and  50  having multiple parts and being connectable to one another by means of coupling elements so as to be tension-proof and angularly movable. Each plow guide trough has a center piece 21 and 51 with superposed chain guide channels  10 C,  10 B,  10 D, to both sides of which center piece an end piece,  22,23  and  52,53  is joined by welding, which end piece is a single-piece casting with superposed chain channel sections that are separated by a sliding spacer piece that is cast on. To make available a high-performance Gleithobel system with a high tool life, cast-on holding pockets  24,25  and  54, 55 —which are open on the working face side—for toggle connections with toggles  1  as coupling organs are disposed on end pieces  22,23  and  52, 53 . (FIG.  2 )

[0001] The subject matter of the present invention relates to a plowguide for a chain-pulled plow, with plow guide troughs having multipleparts and being connectable to one another by means of coupling elementsso as to be tension-proof and angularly movable, with each plow guidetrough having a center piece with superposed chain guide channels, toboth sides of which center piece an end piece is joined by welding,which end piece is a single-piece casting with superposed chain channelsections that are separated by a sliding spacer piece that is cast on.

[0002] In underground mining operations, it is known to use plow systemswhich comprise a shiftable chain scraper conveyor which can be used bothas a face conveyor and as a gate conveyor. On the working face side,plow guide troughs are mounted on the conveyor line pans of the chainscraper conveyor, on which plow guide troughs the plow is guided andwhich have chain channels for guiding the endless plow chain disposed onthem so as to be able to pull the plow along the wall face. In modemhigh-performance plow systems, to which the present invention ispreferably addressed, the plow on the plow guide is forcibly guided. Inthe prior art, many measures have already been proposed to reinforce theconveyor line pans and the plow guide troughs so as to keep up with theever-increasing rated capacities of the chain scraper conveyors and theplow drives in high-performance plow systems. Thus, it is known that theplow guides can be disposed on the goaf side and that the plow can bedesigned as a sword plow, with the sword plow extending with a swordunder the chain scraper conveyor (DE 36 27 733) or reaching with a swordbetween the top strand and the bottom strand.

[0003] The present invention relates to guide troughs for Gleithobel*plows which are disposed along the working face side of conveyor linepans of a chain scraper conveyor. In the precharacterizing portion ofthe claim, this invention uses the plow guide troughs according toGerman Patent DE 32 44 038 A1 as a starting point. In the generic plowguide troughs, the entire conveyor line pan, including the plow guidetrough, is designed to comprise three parts, i.e., a center piece andtwo end pieces, so as to reinforce the individual plow guide troughs andto increase the tool life of the plow system, with at least the endpieces of the plow guide troughs on the working face side being made ofsingle-piece highly refractory castings which, in the form of weldedpieces, have been welded onto the conveyor line pan and onto the centerpiece. In the generic plow guide troughs and conveyor line pans, boththe plow guide troughs on the working face side and the conveyor bottomand the spill plate side on the goaf side is designed in three parts, asa result of which the time required to mount a generic plow guide troughor a conveyor line pan is comparatively high. The coupling elements inthe generic plow guide troughs are bolts which have to be inserted intobolt holes in the spill plate pieces and in the sliding spacer pieces inthe end pieces of the plow guide troughs.

[0004] The problem to be solved by the present invention is to makeavailable a plow guide with plow guide troughs on conveyor line pans ofa high-performance Gleithobel plow system which has a sufficiently hightool life even of the rated capacities of the plow system are high andwhich can be manufactured economically.

[0005] This problem is solved by the invention disclosed in claim 1.Preferred embodiments follow from the dependent claims. According to thepresent invention, the end pieces have holding pockets which have beenjoined by casting and which are open on the working face side, intowhich holding pockets high-duty toggles can be inserted, requiring onlylittle assembly time. Consequently, in the plow guides according to thepresent invention, toggle connections form the coupling elements forconnecting adjoining plow guide troughs in a tension-free manner, andthe three-part design of the plow guide troughs with a center piece andtwo end pieces is retained. To reduce costs, the center pieces can bemass-produced while the end pieces can be produced to accommodatedifferent widths, different coupling elements, or similar requirements.By using toggle connections instead of bolt connections for the genericconveyor line pans, which toggle connections can be inserted intoholding pockets that are integrally joined to the end pieces by castingand which do not require any aftertreatment, it is possible toconsiderably increase the rated capacity of the plow system, while atthe same time avoiding the risk of rupturing the coupling elements.

[0006] To make the end pieces of the plow guide troughs morewearresistant, the end pieces can have a preferably circumferentiallyclosed upper chain channel section, with the possibility that the upperchain channel section of one of the lateral pieces has an overlappingprojection and that the upper chain channel section of the other endpiece has a mating recess for engaging the overlapping projection.Overlapping the end pieces of adjoining plow guide troughs and conveyorline pans minimizes wear due to fine coal abrasion which can be causedby angle formations between the individual conveyor line pans so thatthe tool life of the plow guide and thus the tool life of the entireplow system is increased. The overlapping projection and the matingrecess may be designed in the shape of a ring and preferably in theshape of a centering ring and a mating centering recess so as to sealoff the upper chain guide channel for the return strand of the plowchain. The preferably circular inside cross section of the upper chainchannel section further reduces the susceptibility of the end pieces towear. In a preferred modification, no transverse forces are absorbed ortransmitted with the centering ring and the centering recesses. Toimplement this, the centering ring can conically taper towards its frontside and/or can have a chamfering on its front side while the centeringrecess conically tapers with increasing depth and/or is countersunk onthe bottom. It is also useful if one of the end pieces has anoverlapping tongue above its upper chain guide channel section or in theregion abutting the upper chain guide channel section and if the otherend piece has a matingly overlapping slot with which the overlappingtongue mates so as to keep the overlapping parts on the chain guidechannels free from the forces acting in the transverse direction.

[0007] To further minimize the seepage and deposition of fine coal dustin the upper chain guide channel, the center pieces of the plow guidecan be made of a single-piece casting with a circumferentiallycontinuous upper chain guide channel. For the purpose of inspection andsimple assembly of the return strand of the plow chain, the centerpieces of at least some plow guides can be made of a casting base withan access opening to the upper chain channel section, which accessopening can be closed with a detachably attached hood. In the closedposition, the outer surface of the hood preferably is aligned with theouter surface of all end pieces as well as the outer surfaces of thecenter pieces that are made of a single-piece casting. To facilitate theaccessibility to the pulling strand of the plow chain, it is especiallyuseful if the upper chain channel section in the casting base, in whichthe access opening is disposed, has a bottom opening leading to thelower chain channel section, which bottom opening can be filled with aninsert piece, preferably an insert screen with suitable openings forallowing fine coal to pass through. Using the insert screen can ensurethat during operation of the plow system, fine coal from the otherwiseclosed upper chain guide channel is discharged into the lower chainguide channel. The detachable insert piece replaces the sliding spacerpiece (not present in the casting base) in the region of the bottomopening, with its upper surface being suitably designed in the shape ofa rounded groove. It is to be especially preferred if the insert piececan be inserted and locked into the bottom opening without fasteningelements or screws which require the use of a tool. Thus, the insertpiece can have lugs disposed on the front and rear long side, and thecasting base can have pocket inserts for the lugs, which pocket insertshave edges that are open toward the bottom opening. The insert piecewhich is inserted with its lugs into the appropriately designed pocketslots is subsequently affixed so as to face downwardly and in thedirection of travel of the plow chain. The insert piece preferably has astep disposed on the front long side, in the center of which step theforwardly projecting lug is formed, and the hood has a minimum of onelongitudinal crosspiece disposed on the lower surface of the hood, whichcrosspiece, in the assembled state, abuts the step so as to be able toaffix the insert piece only by inserting the hood into the bottomopening. It is useful for the rear surface of the hood to be designed asa preferably rounded groove section for bounding the upper chain guidechannel.

[0008] The hood is locked to the casting bases preferably by means ofself-locking screws which have plate-shaped caps with rectangularlocking attachments and which can be inserted into indentations on theupper surface of the hood, which recesses have a rectangular crosssection. The locking screws preferably have a bolt screw disposed on theunderside of the cap and can be screwed with a nut to the casting basefrom the goaf-side rear. To avoid an unintentional detachment of thehood as a result of vibrations, the hood can have a mounting hole for adamping element disposed between two indentations.

[0009] In the especially preferred embodiment, the three-part plow guidetrough itself forms the working face side of a conveyor line pan, with asingle-piece intermediate metal sheet which extends continuously throughthe center piece and both end pieces or a single-piece continuousconveyor bottom being joined by welding to the goaf-side rear of theplow guide trough. The configuration with an intermediate metal sheetoffers the advantage that the top strand of the chain scraper conveyorfor each conveyor line pan can be designed as a two-way trough. To makemounting the intermediate metal sheet easier, the rear surfaces of thecenter piece and the end pieces can have projecting cast-on attachments,to which the intermediate metal sheet can be joined by welding. It isalso to be preferred if the bottom of the bottom strand for the line panis an angled bottom metal sheet which is joined by welding and whichextends over the entire length of the center piece and the two endpieces. To further reduce the cost, the lateral profiles for guiding thescrapers in the bottom strand of the chain scraper conveyor do not havespecific design features.

[0010] To operate a plow system with the plow guides and conveyor linepans according to the present invention, it is especially useful if theribs are welded on underneath the bottom metal sheet, both on theworking face side and on the goaf side, with the underside of the ribson the goaf side preferably having a curved design so as to serve aselastic arches which make it easier for the plow guide to climb when theplow system advances. The toggle connections preferably comprise toggleswith toggle heads on both toggle ends, which toggles can be preventedfrom falling out or being detached by providing suitable retentionelements in the pocket recesses that open toward the outer surfaces ofthe plow guide troughs. In particular, the toggle heads of the togglescan have tongues disposed on them, which tongues on one end mate withmating slots in the pocket recesses, thus making it possible for aretention element to be disposed only on one end of the toggles.

[0011] Additional advantages and embodiments of the plow guide accordingto the present invention follow from the dependent claims and thesubsequently following description of practical examples of conveyorline pans and troughs of a plow system which are diagrammaticallyrepresented in the drawing. In the drawing:

[0012]FIG. 1 shows a partially broken top view of two plow guide troughsand conveyor line pans of a plow system;

[0013]FIG. 2 shows the plow guide troughs of the plow system accordingto FIG. 1, with a view of the working face side of the plow system;

[0014]FIG. 3 shows a partially broken view of the front side of plowguide troughs according to the present invention;

[0015]FIG. 4 shows a sectional view along line IV-IV seen in FIG. 1;

[0016]FIG. 5 shows a perspective view of a hood which is used in some ofthe plow guide troughs according to the present invention;

[0017]FIG. 6 shows a plan view of the insert screen which can beinserted into the center piece in plow guide troughs having an opening;

[0018]FIG. 7 shows a sectional view along line VII-VII seen in. FIG. 6;and

[0019]FIG. 8 shows a lateral view of a detail of the locking screw usedto affix the hood.

[0020]FIGS. 1 and 2 show two conveyor line pans 2,3 for a plow system,which conveyor line pans are arranged side by side and are connected toone another so as to be tension-proof but angularly movable, with, inFIG. 1, the lower side of conveyor line pans 2,3 which faces the workingface side comprising plow guide troughs, referenced overall by referencenumerals 20 and 50, on which a Gleithobel (not shown in detail) isforcibly guided. Except for the differently designed plow guide troughs20,50 on the working face side, conveyor line pans 2,3 are of identicaldesign, as can be especially well seen in FIGS. 2 and 3. As shown inFIG. 3, each conveyor line pan 2,3 has a profiled side wall 4 on thegoaf side, with attaching parts 7 projecting upwardly, with side walls 4being connected via an angled bottom strand metal sheet 5 and anintermediate bottom 6 to plow guide troughs 20 and 50 to form aflexurally rigid structure. Intermediate bottom 6 bounds a top strandvat-holding space for holding a top strand vat, referenced overall byreference numeral 8, which top strand vat is designed as a workingtrough and can be removed by lifting it upwardly from conveyor line pans2,3. Bottom strand metal sheet 5 and the inside surfaces 9 of thelateral profiles 4 and 11 of plow guide troughs 20,50 bound a bottomstrand 12 for the return strand of a chain scraper conveyor (not shownin detail). Below the bottom metal sheet 5 of the bottom strand, ribs 13are welded on on the goaf side, which ribs, on their lower surface 13′,are arched in a bow-like fashion so that ribs 13 not only ensure areinforcement between bottom metal sheet 5 and lateral profile 4 on thegoaf side but also an elastic support of the plow system on the goafside. On the working face side, additional ribs 14 are welded on belowplow guide troughs 20,50 and angled bottom metal sheet 5. To make iteasier to join bottom metal sheet 5 of the bottom strand andintermediate bottom 6 by welding, both lateral profiles 4 and plow guidetroughs 20,50 have attachment points 15,16 or steps disposed on theirinside surfaces.

[0021] The present invention relates in particular to the multi-partstructure of plow guide troughs 20,50 which bound conveyor line pans 2,3on the working face side. As can be especially well seen in FIGS. 1 and2, both the right-hand plow guide trough 20 and the left-hand plow guidetrough 50 are constructed of three parts that are welded together, withboth plow guide troughs 20,50 having a long center piece 21,51, towhich, on both ends, end pieces 22,23 and 52,53 are welded on, which endpieces are made of castings with integrally cast-on toggle holdingpockets 24,25 and 54,55. Plow guide troughs 20 and 50 differ only as tothe design of their center piece 21 and 51, respectively, while endpieces 22 and 52 and 23 and 53, respectively, which are made ofcastings, are identically designed. End pieces 22 and 52 have toggleholding pocket halves 24 and 54 with undercuttings on the butt joints,in which undercuttings the left (as seen in the figures) head 18 oftoggle 1 can be form-fittingly anchored with its associated toggle headtongue 18′ without the need of other retention elements. Therespectively other toggle holding pocket half 25 and 55 comprises apocket extension 26 and 56 for a detachable toggle retention element 19which extends over the tongue on the other toggle head.

[0022] As is shown in FIGS. 1, 3 and 4 by way of an example, both theend pieces 22,52,23,53 and the center pieces 21,51 of plow guide troughs20 and 50 have an upper chain channel 10A, 10C and 10D for the returnstrand of the plow traction chain and a lower chain channel 10B for thepulling strand of the plow chain. The lower chain channel 10B is opentoward the face so that a plow (not shown in detail) can be forciblyguided on slide rail 70 of plow guide troughs 20,50—which slide railbounds the lower chain channel 10B on the face side—by means of armattachments which engage in the lower chain channel 10B where they areconnected to the pulling strand of the plow chain. At the same time, theGleithobel runs on slideway 71 which on all plow guide troughs 20,50projects beyond slide rail 70 on the face side.

[0023]FIG. 3 also clearly shows that the upper chain guide channel 10Ahas a circular cross section and is circumferentially closed. As FIGS. 1through 3 also show, end pieces 22,52 of plow guide troughs 20 and 50have centering pins 72 which project beyond the front sides of endpieces 22,52 and which can engage in mating centering recesses on endpieces 23 and 53 of the plow guide troughs. End pieces 22 and 52 eachhave a centering ring 27 and 57, respectively, which centering ringprojects beyond the front side and which tapers conically toward its tipand mates with a correspondingly designed centering recess 28 in endpieces 23 and 53, which centering recess tapers conically as its depthincreases. The conically tapering centering ring 27,57 has a chamferingdisposed on its front end. The conically tapering centering recess 28 ismatingly countersunk. Between centering ring 57 and centering recess 28,sealing surfaces form, which sealing surfaces prevent coal dust fromentering or exiting along the joint between the conveyor line pans.Centering rings 27 and 57 form an extension of the upper chain channelsection 10A that projects beyond the associated end piece 22 and 52,respectively, so that when angles form along the joint between twoneighboring plow guide troughs 20,50 in the region of the upper chainchannel 10A, it is not possible for fine coal to enter between plowguide troughs 20 and 50. Transverse forces between conveyor line pans2,3 and plow guide troughs 20,50 are preferably not transmitted by wayof mating centering rings 27,57 and centering recesses 28 butexclusively by way of centering pins 72 and the mating recesses and byway of overlapping tongues 74 and overlapping slots 75 above the upperchain guide channel 10A.

[0024] As FIG. 1 indicates, the two conveyor line pans 2,3 differ onlyas to the construction and design of the center pieces 21 and 51 forplow guide trough 20 and 50. Center piece 21 which is a casting has across section that is constant throughout its length, with acircumferentially closed upper chain guide channel 10C, with conical orchamfered circular expansions 29A and 20B being disposed along thetransition region from the upper chain channel sections 10A of the sidepieces 22,23 to the chain guide channel 10C in the center piece 21,which expansions ensure that along the welded joint between end pieces22,23 and center piece 21, the plow chain can travel without touchingabutted edges even in the presence of mounting inaccuracies.

[0025] Center pieces 51 differ from center pieces 21 in that centerpiece 51 has an access opening 58 in the front section 58A—facing theworking face side—of a casting base 59, which front section forms aloading ramp. Via access opening 58, the return strand of the plowchain, which return strand is installed in the upper chain guide channel10D, 10A, can be accessed, and opening 58 is closed by means of a hood60 which is anchored in opening 58 by means of two locking screws 80. Asseen in FIGS. 1 and 4, access opening 58 also leads to an access to thelower chain guide channel 10B since, in addition to access opening 58 inthe loading ramp, casting base 59 also has a bottom opening 78 in thetransition region from upper chain channel 10D to lower chain channel10B. Bottom opening 78 is closed by means of an insert piece 90 which isdesigned as an insert screen.

[0026] The design of casting base 59, hood 60, locking screws 80 andinsert screen 90 will be explained below in greater detail withreference to FIGS. 4 through 8. On front side 61, hood 60 which isperspectively shown in FIG. 5 has a curved design which corresponds tothe curvature of front side 5 8A of center piece 51, which front sideserves as a loading ramp, while rear side 62 of the hood is circularlycurved so as to complement the circular shape of the upper chain channel10D in center piece 51. On the lower side, hood 60 has two longitudinalcrosspieces 63,64, the distance between which is greater than the depthof slide rail 70 (FIG. 4). The anterior longitudinal crosspiece 63 abutsa longitudinal ledge 76 disposed on the upper side of slide rail 70, asa result of which hood 60 in opening 57 is locked against horizontalmovements perpendicular to the direction of chain travel. The rearlongitudinal ledge 64 rests on lug 91 which faces the working face sideand which is located in the center of insert screen 90, as a result ofwhich insert screen 90 is affixed on the working face side in opening78. As especially well seen in FIG. 7, lug 91 is an extension of step 99on the front side 98 of insert screen 90 and is set off against upperside 92 of insert screen 90, which upper side is curved in a groove-likemanner.

[0027] In the upward direction, rear side 62 of hood 60 ends in arounded lug 65 which extends along the entire length of hood 60 andabove which stop ledge 66 for detachably locking hood 60 in opening 58is disposed. Stop ledge 66 has two rectangular indentations 67 disposedin it, which indentations mate with one locking lug 83 each—whichlocking lug has a rectangular cross section and projects laterallybeyond screw bolt 82—of caps 81 of locking screws 80 (FIG. 8). Lockinglugs 83 are tightened against the front side of casting base 59 by meansof nuts 84 which, from the goaf side, are screwed onto screw bolts 82that pass through the holes in casting base 59 in the region ofindentations 67, with the bottom sections 68 of indentations 67 beingclamped between locking nuts 83 on caps 81 of locking screws 80 and thefront side of casting base 59 so as to anchor hood 60 in its upperlocking ledge 66 as well. To protect locking screws 80 and the hoodfastener, casting base 59 ends in rail 77, the cross section of whichhas the shape of a T. At the midpoint between the two indentations 67,hood 60 also has a mounting hole 69 for a damping element (not shown indetail).

[0028] Insert screen 90 which can be detachably anchored withoutadditional screw fastener in bottom opening 78 of casting base 59 isshown in detail in FIGS. 6 and 7. In addition to step 99 and central lug91 which are pushed against the downwardly tapering bounding wall of thebottom opening by means of one of the longitudinal ledges of the hood,insert piece 90 has two additional lugs 95 disposed on its goaf-siderear side 94, which lugs, on the upper end of the groove-shaped upperside 92, project backwardly. Furthermore, insert screen 90 haslongitudinal slots 96 which form open passages for discharging fine coaldust from the.upper chain guide channel, and in lug 91, the insertscreen has opening 97 for engaging a tool for mounting and dismountinginsert screen 90.

[0029]FIG. 1 shows that insert screen 90 with its goaf-side lugs 95 isseated in open-edged pocket slots 79, with lugs 95 being engaged inpocket slots 79 in such a way that in the mounted state, insert screen90 is secured on the goaf side against vertical movements and axialmovements in the direction of travel of the plow chain.

1. A plow guide for a chain-pulled plow, with plow guide troughs (20;50)having multiple parts and being connectable to one another by means ofcoupling elements so as to be tension-proof and angularly movable, witheach plow guide trough (20;50) having a center piece (22;51) withsuperposed chain guide channels (10C,10B; 10D), to both sides of whichcenter piece an end piece is joined by welding, which end piece is asingle-piece casting with superposed chain channel sections (10A,10B)that are separated by a sliding spacer piece that is cast on,characterized in that the end pieces (22,23; 52,53) have cast-on holdingpockets (23,25; 54,55) for toggle connections as coupling elements,which holding pockets are open on the working face side.
 2. The plowguide as claimed in claim 1, characterized in that the end pieces(22,23; 52,53) have a preferably circumferentially closed upper chainchannel section (19A), with the upper chain channel section (10A) of oneof the two lateral pieces having an overlapping projection (27; 57) andwith the upper chain channel section of the other end piece (23;53)having a mating recess (28).
 3. The plow guide as claimed in claim 2,characterized in that the overlapping projection (27; 57) and the recess(28) are circularly designed and are preferably designed as a centeringring (27; 57) and a centering recess (28).
 4. The plow guide as claimedin claim 3, characterized in that the centering ring (57) tapersconically towards its font side and/or is chamfered on its front sideand that, with increasing depth, the centering recess (28) tapersconically and/or is countersunk on its bottom.
 5. The plow guide asclaimed in any one of claims 1 through 4, characterized in that one ofthe end pieces (22,23; 52,53) has an overlapping tongue (74) disposedabove its upper chain guide channel section (10A) or in the regionabutting the upper chain guide channel section (10A) and that the otherend piece (22;52) has a mating overlapping slot (75).
 6. The plow guideas claimed in any one of claims 1 through 5, characterized in that thecenter piece (21) is a single-piece casting with a circumferentiallyclosed upper chain guide channel (10C).
 7. The plow guide as claimed inany one of claims 1 through 5, characterized in that the center piece(51) is a casting base (59) with an access opening (58) toward the upperchain channel section (10D), which opening can be closed by means of adetachably affixed hood (60).
 8. The plow guide as claimed in claim 7,characterized in that a bottom opening (78) is disposed between theupper chain channel section (10D) in the casting base (59) and the lowerchain channel section (10B), which bottom opening can be filled by aninsert piece, preferably an insert screen (90).
 9. The plow guide asclaimed in claim 8, characterized in that the upper side (92) of theinsert piece (90) preferably has the shape of a rounded groove.
 10. Theplow guide as claimed in claim 8 or 9, characterized in that the insertpiece has projecting lugs (91,95) disposed on the front and rear longside (98,94) and that the casting base (59) has pocket slots (79) forthe lugs (95).
 11. The plow guide as claimed in one of claims 8 through10, characterized in that the insert piece (90) has a step (99) disposedon the front long side (98), on the center of which step a forwardlyprojecting lug (91) is disposed.
 12. The plow guide as claimed in anyone of claims 1 through 11, characterized in that the rear side (62) ofthe hood has a preferably rounded section to bound the upper chain guidechannel (10D) and/or that the lower side of the hood has at least onelongitudinal crosspiece (64) disposed on it, which longitudinalcrosspiece, in the mounted state, abuts the step (99) of the insertscreen (90) so as to mount the insert piece (90) on the bottom opening(78).
 13. The plow guide as claimed in any one of claims 7 through 12,characterized in that the hood (60) has indentations (67) on the upperside of the hood, into which indentations the locking lugs (83) on caps(81) of locking screws (80) can be inserted, which locking screws (80)have a screw bolt (82) on the lower side of the caps (81) and can bescrewed from the working face side to the casting base (59) by means ofa nut (84).
 14. The plow guide as claimed in any one of claims 7 through13, characterized in that in the hood, a mounting hole (69) for adamping element is disposed between two indentations.
 15. The plow guideas claimed in any one of claims 1 through 14, characterized in that thethree-part plow guide trough (20; 50) forms the boundary of a conveyorline pan (2,3) on the working face side and that a single-pieceintermediate metal sheet (6) which extends continuously along the centerpiece (21; 51) and the end pieces (22,23; 52,53) or a continuousconveyor bottom is joined by welding to the goaf-side rear side of theplow guide trough (20,50).
 16. The plow guide as claimed in any one ofclaims 1 through 15, characterized in that the rear side of the centerpiece (51) and the end pieces has projecting cast-on attachments (16)for joining an intermediate metal sheet (6) by welding disposed on it.17. The plow guide as claimed in any one of claims 1 through 16,characterized in that the bottom (5) of the bottom strand for theconveyor line pan is made of an angled, welded-on bottom metal sheetwhich extends in one piece over the center piece and the two end pieces.18. The plow guide as claimed in claim 17, characterized in that on theworking face side and/or on the goaf side, ribs (14; 13) are welded onbelow the bottom metal sheet (5), with the goaf-side ribs (13) beingdesigned so as to be curved on the lower side (13′).
 19. The plow guideas claimed in any one of claims 1 through 18, characterized in that thetoggle connections have toggles (1) with toggle heads (18) on bothtoggle ends.
 20. The plow guide as claimed in any one of claims 1through 19, characterized in that the top strand (8) of the chainscraper conveyor is a two-way trough.